Earthen storage for volatile liquids and method of constructing same



Nov. 29, 1966 P. s. MASSEY 3,

EARTHEN STORAGE FOR VOLATILE LIQUIDS AND METHOD OF CONSTRUCTING SAME Filed Aug. 19, 1963 2 Sheets-Sheet l LIQUID IN LIQUID OUT F ROZ E N EARTH UNFROZEN EARTH INVENTOR.

F. 5. MA 5 S EY A TTOPNEYS United States Fatent O 3,287,915 EARTHEN STORAGE FOR VOLATILE LIQUIDS AND METHOD OF CONSTRUCTING SAME Phillip S. Massey, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 19, 1963, Ser. No. 302,884 Claims. (Cl. 61-.5)

This invention relates to the storage of volatile liquids. In one aspect it relates to a method for preparing a reservoir in the surface of the earth for the storage of volatile liquids. In another aspect it relates to an open-topped earthen reservoir in frozen earth having a vapor-impermeable cover thereover.

The petroleum industry produces great quantities of volatile liquid hydrocarbons as a result of processing crude oil and natural gas. Volatile liquids such as propane and butane require enormous storage facilities during periods of slack use. Increased seasonal demand for such products places an increased strain on these facilities. Great quantities of volatile liquids including propane and butane have been stored in underground caverns mined or dissolved from impervious formations. Such reservoirs, however, are limited to certain formations which are not always available at the desired location; are expensive to prepare; and present a serious problem of providing adequate vapor seals. More recently it has been proposed to fill an open-topped earthen reservoir with water, refrigerate the reservoir so as to freeze an ice cap on the water, pump out the water and fill the reservoir with a volatile liquid. Such reservoir is disclosed and claimed in Patent Number 2,961,840 issued November 29, 1960, to W. A. Goldtrap.

According to my invention an insulated, vapor-imper meable roof over an earthen reservoir in frozen earth is supported by, and sealed to, a vapor-impermeable wall which extends downwardly from the roof and into the frozen earth. The vertical wall has a base plate attached perpendicularly to its bottom edge. The lower portion of the wall is positioned in a trench in the earth which is filled with a plastic material such as mud which is frozen so as to seal the wall rigidly in the earth. The frozen mud provides a vapor-impermeable seal around the wall and also provides a firm support for the roof. The base plate can rest upon the undisturbed earth in the bottom of the trench or can be suspended in mud during the freezing of the earth adjacent the earthen reservoir.

The roof and wall will usually be made of metal such as steel or aluminum, however any construction material which is vapor impermeable and not adversely affected by the temperatures involved can be used. The material should be capable of flexing to cope with expansion and contraction and movement of the earth as a result of temperature changes involved.

The plastic material used to fill the trench can be any slurry of solids in a liquid which will freeze at the temperature contemplated for the reservoir. An ordinary slurry of earth and water is satisfactory. The solids in the slurry do not expand upon being frozen so that the expansion of the slurry is much less than that of water alone. The ratio of water to solids is not critical so long "ice roof over an earthen reservoir in the frozen surface of the earth. Still another object is to provide a roof support for an open-topped earthen reservoir in frozen earth. Another object is to provide a vapor-impermeable seal for sealing a roof to an open topped earthen reservoir in frozen earth. Other objects and advantages will be apparent to one skilled in the art upon studying the disclosure of the invention including the detailed description and the appended drawing wherein:

FIGURE 1 is a view in cross-section of one side of an earthen reservoir with a roof seal and support of my invention; and

FIGURE 2 is a plan view of a segment of the reservoir of FIGURE 1 with a portion of the roof removed.

In FIGURE 1 a reservoir 10 is excavated in frozen earth 11. The earth is frozen by means of a plurality of freeze pipes sunk into the ground around the site of the reservoir 10. The freeze pipes each comprise a casing 12 and an inlet pipe 13. A refrigerant is supplied to inlet pipe 13 via conduit 14, manifold 15, and conduit 16 from a refrigeration system (not shown). Several banks of freeze pipes can be utilized as desired as indicated at 12a and 13a. Refrigerant vapors are removed from conduit 12 via conduit 17, manifold 18 and conduit 19 to the refrigeration system. The refrigeration system can be a conventional compressor and condenser combination.

A trench 21 is formed in the earth and the wall 22 with the base plate 23 attached is positioned in the trench. The trench is then filled with a fluid slurry of earth and water 24 and the slurry is frozen so as to seal the wall 22 rigidly in the earth.

as there is suflicient water present to form the continuous The insulated roof 25 is secured to the wall 22 and sealed by welding at 26. Discharge conduit 27 and pump 28 and inlet conduit 29 are positioned in roof 25.

Insulation 30 is placed around the reservoir to insulate the sides of the wall 22, the freeze pipe assembly and the surface of the frozen earth.

. The relatively small amount of movement or heaving of the frozen earth at the site of the reservoir is compensated by flexure of the roof 25 and the Wall 22.

The invention will now be described as applied to a circular earthen reservoir feet in diameter and 95 feet in depth. A first Ill-foot diameter circle and a second 1l7-foot diameter circle of freeze pipes are sunk about feet into the ground. Liquid refrigerant is supplied to the bottom of the freeze pipes by tubing which extends nearly to the bottom of the freeze pipes. Liquid propane is utilized as refrigerant.

A trench about 4 feet deep and about 3 feet wide at the top is dug around the site of the reservoir so as to include the inner circle of freeze pipes before the freezing operation is started. A ring wall 6 feet in height of inch thick tank steel plate, having l-foot wide A-inch plate welded perpendicularly to its bottom edge, is positioned in the trench and the trench is filled with a fluid slurry of water and finely divided clay.

The portion of the ring wall and the freeze pipes which projects above the grade level is then covered with crushed rock and insulation and freezing is begun. Excavation of the reservoir is begun about 2 months after freezing is started. The exposed frozen wall of the reservoir is insulated as excavation progresses.

The roof is then fabricated and welded to the top of the ring wall. The roof is dome-shaped and is supported by a plurality of trusses which radiate from the center and rest on the ring wall. The truss structure is assembled -on the ground adjacent the reservoir and is then placed in position by two cranes. The steel plate covering is welded in place to provide a vapor-tight cover.

0 The roof is then insulated with glass wool bats and covered with a weather-proof polyethylene film sheet.

The insulation is continued around the periphery of the roof past the area of frozen earth.

The metal used in the above storage system for low temperature service, e.g., the freeze pipes, roof and ring wall is weldable steel having superior low temperature impact properties, Steel for such service is commercially available.

The above reservoir is for the storage of liquid propane at substantially atmospheric pressure. Other volatile liquids such as liquefied natural gas; liquefied methane, ethane or butane; and the like, can be stored in the above reservoir by choosing the proper refrigerant.

That which is claimed is:

1. The method of providing a vapor seal for the top of an earthen. storage system for normally gaseous liquid wherein an open-topped earthen reservoir in frozen earth is covered with a vapor-impermeable insulated roof and the earth adjacent the reservoir is maintained frozen by means of a plurality of freeze pipes positioned in the earth around said reservoir which method comprises forming a trench in the earth adjacent the periphery of the reservoir between the reservoir and freeze pipes; positioning in said trench the lower portion of a continuous, enclosing vertical, vapordmpermeable wall capable of supporting the roof having a horizontal base plate fixedly attached to its bottom; filling said trench with a plastic material comprising a slurry of solids in a liquid capable of being frozen by the frozen earth; and sealing the insulated reservoir roof to said wall in the plastic material when frozen to support said roof and to form a vapor tight enclosure for the reservoir top.

2. A combination roof support and vapor barrier for use in an earthen storage system for normally gaseous liquid having an opentopped earthen reservoir maintained in frozen earth by means of a plurality of freeze pipes located around the periphery of the reservoir, said combination comprising a trench in the frozen earth around the periphery of the reservoir; an insulated, vaporimpermeable roof covering said reservoir; a continuous, enclosing, roof supporting, vapor-impermeable wall extending downwardly from the roof and terminating in said trench; a base plate fixedly secured horizontally tothe bottom of said wall; and a frozen slurry of solids in a liquid filling said trench so as to support said wall and said roof and to form a vapor-impermeable seal with said wall.

3. An earthen storage system for normally gaseous liquid comprising an open-topped earthen reservoir in frozen earth; freeze pipes located around the periphery of the reservoir and extending into the earth so as to keep the earth adjacent the reservoir frozen; a trench in frozen earth around the periphery of the reservoir; a vaporimpermeable roof covering said reservoir; a continuous, enclosing, roof supporting vapor-impermeable wall sealed to said roof and extending downward into said trench; and a frozen slurry of solids in a liquid substantially filling said trench so as to support said wall and to seal said wall to the frozen earth.

4. In an earthen storage systemfor normally gaseous liquid comprising an open-topped earthen reservoir in frozen earth having a plurality of freeze pipes positioned in the earth around the reservoir to maintain the earthen Walls of the reservoir frozen and having an insulated roof covering said reservoir, the combination therewith of a trench in the frozen earth around the periphery of the reservoir; a vertical, continuous, enclosing, vapor impermeable, roof supporting wall positioned in said trench with the top in sealing and supporting contact with said roof; and a frozen slurry of solids in a liquid substantially filling said trench.

5. The combination of claim 4 wherein a base plate is secured to the bottom of the wall at a right angle to the vertical plane of the wall.

References Cited by the Examiner UNITED STATES PATENTS 1,100,081 6/1914 Kramer 52-247 X 2,036,047 3/1936 Hill 52170 X 3,159,006 12/1964 Sliepcevich 61.5 X 3,175,370 3/1965 Schlumberger et al. 61.5 X 3,195,310 8/1965 Schroeder 6l-5 3,205,665 9/1965 Van Horn 6l.5

FOREIGN PATENTS 111,569 3/ 1962 Pakistan.

EARL I. WITMER, Primary Examiner. 

2. A COMBINATION ROOF SUPPORT AND VAPOR BARRIER FOR USE IN AN EARTHEN STORAGE SYSTEM FOR NORMALLY GASEOUS LIQUID HAVING AN OPEN-TOPPED EARTHEN RESERVOIR MAINTAINED IN FROZEN EARTH BY MEANS OF A PLURALITY OF FREEZE PIPES LOCATED AROUND THE PERIPHERY OF THE RESERVOIR, SAID COMBINATION COMPRISING A TRENCH IN THE FROZEN EARTH AROUND THE PERIPHERY OF THE RESERVOIR; AN INSULATED VAPORIMPERMEABLE ROOF COVERING SAID RESERVOIR; A CONTINUOUS, ENCLOSING, ROOF SUPPORTING, VAPOR-IMPERMEABLE WALL EXTENDING DOWNWARDLY FROM THE ROOF AND TERMINATING IN SAID TRENCH; A BASE PLATE FIXEDLY SECURED HORIZONTALLY TO THE BOOTH OF SAID WALL; AND A FROZEN SLURRY OF SOLIDS IN A LIQUID FILLING SAID TRANCH SO AS TO SUPPORT SAID WALL AND SAID ROOF AND TO FORM A VAPOR-IMPERMEABLE SEAL WITH SAID WALL. 